This invention relates to applicators and/or dispensers for dispensing and/or applying an adhesive material, for example, a polymerizable monomer compound such as a cyanoacrylate adhesive, particularly for medical use.
Numerous swabs, applicators, dispensers and kits for dispensing and applying various materials, including adhesive materials, are known. However, these known arrangements possess various shortcomings that make them undesirable in many applications.
Monomer and polymer adhesives are used in both industrial (including household) and medical applications. Included among these adhesives are the 1,1-disubstituted ethylene monomers and polymers, such as the α-cyanoacrylates. Since the discovery of the adhesive properties of such monomers and polymers, they have found wide use due to the speed with which they cure, the strength of the resulting bond formed, and their relative ease of use. These characteristics have made the α-cyanoacrylate adhesives the primary choice for numerous applications such as bonding plastics, rubbers, glass, metals, wood, and, more recently, biological tissues.
Medical applications of 1,1-disubstituted ethylene monomer adhesive compositions include use as an alternate or an adjunct to surgical sutures and staples in wound closure as well as for covering and protecting tissue wounds such as lacerations, abrasions, burns, stomatitis, sores, and other open surface wounds. When such an adhesive is applied, it is usually applied in its monomeric form, and the resultant polymerization gives rise to the desired adhesive bond.
Applicators for dispensing a polymerizable and/or cross-linkable material, such as a 1,1-disubstituted ethylene formulation, are disclosed in U.S. Pat. No. 5,928,611 to Leung and copending U.S. patent application Ser. No. 09/430,177, filed Oct. 29, 1999. In general, many different 1,1-disubstituted ethylene formulations are known for various applications, for example, cyanoacrylate formulations used as fast-acting surgical adhesives, sealants, bioactive agent release matrixes and implants utilized in medical, surgical and other in vivo applications. Such formulations include those disclosed by Leung and the references cited therein.
However, due to the need to apply the adhesive in its monomeric form, and due to the rapid polymerization rate of the monomers, it has been very difficult to design effective and commercially viable applicators and/or dispensers. Such applicators and/or dispensers must counterbalance the competing requirements that the monomer not prematurely polymerize, that the monomer be easily applied, that the monomer polymerize at a desired rate upon application, and that the sanitary and/or sterile properties of the monomer and applicator—whether real or perceived—be maintained. This latter requirement, that the actual or perceived sanitary and sterile condition of the monomer and applicator be maintained, is particularly important in medical applications, where the user and/or the patient desires a clean product so as not to introduce further bacteria or foreign matter into a wound site.
A further problem in addressing the above requirements of adhesive applicators and/or dispensers is the need to provide a stable monomer product. Particularly in small quantities, cyanoacrylate monomers are prone to premature polymerization, which would render the product useless. Thus, industrial production of monomeric adhesive compositions has had to balance rapid cure rates and high bond strengths with shelf-life. The shelf-life of these adhesives is primarily related to stability (i.e., constancy of compositional nature), uncured physical properties, rate of cure of the adhesive, as well as final cured properties of the composition. For example, the shelf-life of a monomeric α-cyanoacrylate composition may be measured as a function of the amount of time the composition can be stored before unacceptable levels of polymerization, such as measured by viscosity increase, occur. Unacceptable levels are indicated by a level of polymerization product that reduces the usefulness of the composition in the application for which it is produced.
Known devices fail to provide an applicator and/or dispenser that is optimized for convenient dispensing and application of adhesive materials on a variety of surfaces and structures. The known applicators are generally either optimized for delivery of other compositions or are inconvenient for use in conjunction with adhesives. Furthermore, such conventional devices generally do not address the competing needs of ease of use and adhesive stability prior to application.